RU2570490C2 - Assembly of component without plasticity region - Google Patents

Abstract

FIELD: physics; clocks.

SUBSTANCE: invention particularly relates to production of clock mechanisms. The invention relates to assembling an element (15) made of a first material with a component (3) made of a second material without a plasticity region, which includes the following steps: a) forming a component (3) with an opening; b) inserting an intermediate component (7), made of a third material and having an opening, into an opening without generating stress; c) inserting an element (15) into the opening without generating stress; d) elastically and plastically deforming the intermediate component (7) by moving two instruments (13, 21) towards each other in an axial direction respectively on the upper and lower parts of the intermediate component to generate, on the element and the surrounding opening on the wall of the component (3), radial stress which causes elastic deformation of the component (3) to tighten the unit without breaking the component.

EFFECT: preventing breakage of tightened components.

17 cl, 11 dwg

Description

FIELD OF THE INVENTION

The invention relates to the assembly of a part made of a material having no plasticity region with an element containing another type of material.

State of the art

Currently, assemblies including silicon-based parts are usually bonded with adhesive joints. This type of operation requires a very accurate application of glue, which makes this technology expensive.

EP 2107433 describes that a first silicon-based part is mounted on an intermediate metal part, and then the entire assembly is mounted on a metal axis. However, embodiments of the invention proposed herein are not satisfactory and either result in breakdown of the silicon-based part during assembly or do not provide the required fastening of the parts.

Indeed, in this document, one edge of the intermediate part is folded over the silicon part, causing the occurrence of pure axial stresses, which breaks the silicon part. In addition, the document proposes to use faceting, which leads to an uneven distribution of stress in silicon and also causes breakdown of the silicon part.

Disclosure of invention

The objective of the invention is to eliminate all or part of the aforementioned drawbacks by developing an assembly without the use of adhesive joints, which enables assembly of a part made of a material having no plasticity region with an element containing a plastic material, such as, for example, metal or a metal alloy.

Thus, the invention relates to a method for mounting an element made of a first material into a part of a second material without plastic regions. The method includes the steps in which:

a) form a part with a hole;

b) insert the intermediate part, which is made of a third material and has a hole in the hole without creating tension;

c) insert the element into the hole;

d) deform the intermediate part elastically and plastic by moving two tools towards each other in the axial direction, respectively, on the upper and lower parts of the intermediate part to create radial stress on the element and on the part wall around the perimeter of the hole, causing elastic deformation of the part to fasten the assembly without breaking the part .

This method provides the advantage that it allows the element to be fixed in the radial direction without creating axial stresses in the part. Indeed, an advantage of the invention is that the part undergoes only radial deformations.

In addition, this configuration gives the advantage that it provides the fastening of the elements of the node consisting of the part and the intermediate part, without fastening with the usual precisely controlled element, while ensuring the absence of breaking stresses in the part, even if it is performed, for example , made of single-crystal silicon.

And finally, this method connects a node containing an element, part and an intermediate part, by compensating for manufacturing errors of various components.

According to other preferred features of the invention:

- the shape of the outer wall of the intermediate part essentially corresponds to the hole in the part, which ensures the creation of essentially radial stress in the wall of the part surrounding the hole;

- the hole in the part is round;

- the part wall surrounding the hole contains slots, which in step d) form micro-grooves on the outer surface of the intermediate part to prevent relative movement of the assembly elements;

- the outer surface of the element contains slots, which in step g) form micro-grooves on the inner surface of the intermediate part to prevent relative movement of the elements of the node;

- the hole in the part is asymmetric to prevent relative movement of the elements of the node;

- at step b) the difference between the cross section of the hole and the outer section of the intermediate part is about 10 microns;

- in step c), the difference between the cross section of the element and the inner section of the intermediate part is about 10 microns;

- at step d) the deformation creates a compressive force, causing a displacement of 16-40 microns;

- in step b) the intermediate part contains a conical shoulder coaxial with the hole in order to simplify the orientation of the stress caused by the deformation of the intermediate part in step g);

- the second material is formed from the basis of single-crystal silicon;

- the third material is formed of metal or a metal alloy base;

- the part can be, for example, a set of wheels of a clockwork, ratchets of a clockwork, a clockwork spring, a resonator, or even a microelectromechanical system.

Brief Description of the Drawings

Other features and advantages will be apparent from the following description, given by way of non-limiting example, with reference to the accompanying drawings.

Figures 1 and 2 show diagrams of successive steps of an assembly method according to the invention;

figure 3 and 4 is an intermediate part according to the invention, views in section in front and in perspective;

5 and 6 are diagrams of alternative steps of the assembly method of the invention;

7-10 - variants of the intermediate parts according to the invention;

figure 11 is an alternative hole parts made of brittle material.

The implementation of the invention

As described above, the invention relates to an assembly and a method for assembling it for joining a brittle material, i.e. a material without a ductility region, such as a material based on single-crystal silicon, with a ductile material, such as a metal or metal alloy.

This assembly method is designed for use in the watch industry. However, it can also be applied in other areas, in particular, such as the space industry, the jewelry industry, the automotive industry or the manufacture of dishes.

In the watch industry, this assembly method is necessary because of the increasing importance of brittle materials, such as materials based on silicon, quartz, corundum, or, more generally, ceramics. As an example, it is possible to imagine the complete or partial formation of a balancing spring, balancer, jumpers, or even sets of wheels, such as wheels of a travel regulator, in whole or in part based on brittle materials.

However, the need to ensure the use of conventional steel axles, the production of which is already well mastered, is a limitation that is difficult to overcome when using parts that do not have a ductility region. Indeed, when conducting experiments when trying to insert a steel axis, brittle parts were systematically destroyed, i.e. parts without a ductility region. For example, it became clear that the shear stresses generated by inserting a metal axis into the hole of a silicon part systematically cause the part to fail.

In the field of the watch industry, there is a generally accepted opinion that a silicon component cannot withstand voltages of more than 300-450 MPa without destruction. The value of this order was obtained theoretically based on the Young's modulus, which characterizes the zone of silicon plastic deformation.

Therefore, for cases in which the estimated stresses exceed 300-450 MPa, the means of elastic deformation formed by through holes made in silicon were developed similarly to the means described in documents EP 1445670, WO 2006/122873 and WO 2007/099068.

After conducting additional experiments by deforming the intermediate part and gradually increasing the stress in the silicon part, it suddenly turned out that, in fact, the silicon part can withstand a much higher voltage until cracking is detected. So, during the experiments, it was possible to propagate the stresses at which fracture still does not occur, to the range of 1.5-2 GPa, i.e. to values significantly exceeding the generally accepted range of 300-450 MPa. Therefore, generally speaking, brittle materials, such as silicon, quartz, corundum, or, more generally, ceramics, do not necessarily correspond to the statistical models commonly used for brittle materials.

Therefore, the invention relates to the insertion of an element made of a first material, for example a plastic material, such as steel, into the hole of a part made of a second material without a ductility zone, such as a silicon-based material, by deformation of an intermediate part made of a third material which is installed between the element and the part.

According to the invention, the intermediate part has an opening for inserting an element. In addition, the elastically and plastically deformed intermediate part covers in a radial direction or clamps the element, creates elastic stresses in the part and provides such a fixation of the assembly elements, in which there is no destruction of the part.

In addition, it is preferable that the shape of the outer wall of the intermediate part essentially corresponds to the hole in the part, which ensures the creation of essentially radial stress in the wall of the part surrounding the hole. Indeed, after the study, it was found that it is preferable for the intermediate part to evenly distribute the stresses caused by the deformation of the intermediate part along the wall of the part around the hole.

Therefore, if the hole in the brittle part has a circular shape, it is preferable that the outer wall of the intermediate part has a substantially solid cylinder shape, i.e. without radial grooves or through axial holes, in addition to the hole for inserting the element, to prevent local stresses on a small surface area of the part wall around the hole, which can lead to the destruction of brittle material.

Of course, the shape of the hole in a brittle part may be different, for example asymmetric, to prevent relative movement of the assembly elements. Thus, according to a first alternative embodiment, this asymmetric hole may have, for example, a substantially elliptical shape.

According to another alternative embodiment intended to prevent relative movements, as shown in FIG. 11, the wall of the part 3 can be provided with slots 1 extending into the hole 4. Preferably, the slots 1 extend over the entire thickness of the part 3 and comprise a domed outer surface of height h. Of course, the slots 1 can have both a substantially rectangular shape and another shape.

It is clear that these slots 1 with a height h, which is much smaller than the diameter e _{1 of the} hole 4, form micro grooves on the outer surface of the intermediate part when it is deformed, due to which spike-groove joints are formed to prevent rotation of the wall of the hole 4 relative to the outer surface of the intermediate the details.

It is clear that these slots can also be located on the outer surface of the element 5 to obtain the same effect and further improve the connection of the assembled node.

As a result, if the section of the hole has a circular shape, an intermediate part (the shape of which corresponds to the hole), which has a hole, can be considered as a closed ring with continuous internal and external walls, i.e. without any grooves or, more generally, without tearing of the material. Thus, due to elastic and plastic deformation, the shape of the intermediate part corresponding to the shape of the hole ensures the creation of substantially uniformly distributed radial stresses on the maximum surface area of the part wall along the perimeter of the hole.

Of course, the inner wall of the intermediate part, located opposite the element, also has the shape of the wall, providing the interface. As a result, it is obvious that the shape of the inner wall can correspond to the outer shape of the element to create substantially uniformly distributed stresses on the inner wall of the intermediate part at the maximum surface area of the outer wall of the element.

The design of the node according to the invention will become more clear from figure 1-10, which show examples of assembly nodes. Figures 1-4 show a first embodiment of the invention. Thus, the first step involves forming a part 3 having an opening 4 from a material that does not have a ductility region. As shown in figure 1, the hole 4 has a cross-section e ₁ , the size of which is preferably from 0.5 to 2 mm, and the height of the slots 1 shown in Fig. 11, protruding into the hole 4, is respectively 5-25 mm.

This step may be performed using dry or wet etching (e.g., deep reactive ion etching).

Further, in the second stage, the method consists in forming an element representing the rotary axis 5 in the example shown in figures 1 and 2, from the second material with the same main section e ₂ . As explained above, the second step may be performed in accordance with a conventional axis manufacturing process. Element 5 is preferably metallic and may, for example, be formed from steel.

At the third stage, the method consists in forming an intermediate part from the third material with an opening 8 with an internal cross-section e ₄ and an external cross-section e ₃ , the wall of which essentially has a shape corresponding to the shape of the hole 4. The third stage, thus, can be performed using machining and / or electrical molding process. The intermediate part 7 may thus have a thickness in the range of 100-600 μm and a width, i.e. the difference between the outer cross-section e ₃ and the inner cross-section e ₄ divided by two (1 = (е _3- е ₄ ) / 2), in the range of 100-300 microns.

Preferably, the third material is more ductile than the second material of element 5, whereby the latter undergoes less deformation or no deformation at all in the deformation step. The intermediate part 7 is preferably metallic and may include nickel and / or gold. In this case, it is possible to add to the third material any other preferred plastic material or to replace it with a similar material.

Of course, the first three stages should not be considered as a strict sequence and their implementation can even be carried out simultaneously.

In the fourth step, the intermediate part 7 is inserted into the hole 4 in a non-contact manner. This means that, as shown in figure 1, the cross-section e _{1 of the} hole 4 has a larger size or the same size as the outer section e _{3 of the} intermediate part 7.

Preferably, the difference between the cross-sectional size e _{1 of the} hole 4, taking into account the slots 1, if any, and the size of the outer cross-section e _{3 of the} intermediate part 7 is approximately 10 μm, i.e. there is a gap of about 5 μm, which separates the part 3 from the intermediate part 7.

In addition, preferably according to the invention, the intermediate part 7 is held in the hole 4 by means of a tool 11, one of the tools 11, 13 used in the deformation step. And finally, in a preferred manner, the tool 11 has a recess 12 for receiving the element 5.

In the fifth stage, the element 5 is inserted into the hole 8 of the intermediate part 7 in a non-contact manner. This means that, as shown in figure 1, the cross section e _{4 of the} hole 8 is greater than or equal to the outer section e _{2 of the} element 5.

Preferably, the difference between the cross section e _{4 of the} hole 8 and the outer cross section e _{2 of the} element 5 is approximately 10 μm, i.e. there is a gap of about 5 μm, which separates the element 5 from the intermediate part 7.

Further, according to the invention, the element 5 is held in the hole 8 by means of a recess 12 of the tool 11 having a cross section substantially equal to the cross section e _{2 of the} element 5.

And finally, the method includes a sixth step, which consists in elastic and / or plastic deformation of the intermediate part 7 by counter-moving the tools 11, 13 in the axial direction A to create a radial stress C, B respectively on the element 5 and the part wall around the hole 4 behind due to the elastic deformation of the part 3.

Of course, there is no need to make through holes in the part 3 around the perimeter of the hole 4, similar to those described in documents EP 1445670, WO 2006/122873 and WO 2007/099068, to prevent destruction of the part. So, part 3 can undergo elastic deformation even at high stress, i.e. at a voltage of more than 450 MPa for silicon, without cracking.

Thus, as shown in figure 2, the creation of pressure on the upper and lower parts of the intermediate part 7, respectively, with a tool 13 and 11 in the axial direction A causes elastic and plastic deformation of the intermediate part 7, which is deformed only in the radial directions B and C, those. in the direction of part 3 and element 5. After removing the stress from the tools 11 and 13, elastic restoration takes place in part 3, which creates an inseparable connection of the assembly consisting of element 5, intermediate part 7 and part 3.

Preferably according to the invention, the deformation parameters are set so that the compressive force is large in the region of the gaps between the undeformed intermediate part 7 and, on the one hand, the wall of the hole 4, and on the other hand, by the element 5. Preferably, the compressive force creates a movement in the range of 16-40 microns.

As a result, elastic and plastic deformation of the intermediate part 7 is required to create elastic and plastic deformation of the part 3 around the hole 4 and elastic and / or plastic deformation of the element 5 for fastening the element 5, the intermediate part 7 and part 3, as shown in FIG. 2. As shown in FIG. 2, a situation may also arise in which the edge of the intermediate part 7 is wrapped over the part 3 during deformation, without creating any axial stress on the part 3. Finally, it should be noted that this elastic deformation automatically centers the assembly, consisting of element 5, intermediate part 7 and part 3.

Preferably, according to the invention, no axial force is applied to the part 3 during the assembly process (which, by definition, causes damage). In part 3, only elastic radial deformation is created, which is determined by the programmed preset pressure of the tools 13. It should also be noted that the use of an intermediate part 7, the outer wall of which essentially repeats the shape of the hole 4, allows you to create uniformly on the wall of the part surrounding the hole 4 distributed stresses during radial deformation In the intermediate part 7 to prevent destruction of the part 3 made of brittle material, and to compensate for any manufacturing inaccuracies x elements such as, for example, slots 1.

As shown in FIGS. 3 and 4, the intermediate part 7 preferably has a tapered recess coaxial with the hole 8, in order to simplify the strain caused by the deformation of the intermediate part 7 during deformation of the radial orientation B, C and also to provide a gradual increase in said voltage. Of course, the inclined section 9, forming a conical recess 10, leads to the creation of a surface initially in contact with the tool 12, which degenerates into a circle due to radial deformation of the outer wall of the intermediate part 7 in the radial direction with the creation of a gradually increasing force acting on the wall of the part around the hole 4 and to element 5.

In the examples shown in FIGS. 3 and 4, it is seen that the conical recess 10 communicates with the hole 8, forming a flat section between the inclined section 9 and the edge of the hole 8. This feature, i.e. the communication of the conical recess 10 and the hole 8, as shown below, is optional, and the recess 10 and its inclined section 9 may have other shapes and sizes.

Of course, this invention is not limited to the demonstrated example, but contains the potential for specialists in the art to develop various options and make various changes. In particular, part 3 can also be axially fixed in an alternative to the first embodiment.

As an example, FIGS. 5 and 6 show a second embodiment of the method. 5 and 6, an alternative embodiment is shown in which the element 15 is essentially different from the element 5 in that it has a shoulder 16. Thus, the lower part of the tool 21 no longer needs a recess 12 to receive the element 15 but simply provided with a through hole 22, the cross section of which is at least equal to or greater than the cross section of the element 15.

Thus, it is clear that the intermediate part 7 and the corresponding part 3 can be mounted on the shoulder 16. In addition, the deformation of the intermediate part 7 in its lower part in this case is not carried out by the tool 21 itself, but through the shoulder 16 without losing the advantages of this method. Thus, an elastic stress arises in the part 3 in the region of the intermediate part 7 and is fixed relative to the shoulder 16 of the element 15.

As an example, FIGS. 7-10 show a third embodiment of the method. Thus, FIGS. 7-10 show an alternative embodiment in which the intermediate part 27, 27 ′, 27 ″, 27 ″, essentially differs from the intermediate part 7 of the first embodiment of the invention in that it has a shoulder 26, 26 ′ , 26 ", 26 '". As a result, in the third embodiment of the invention, the same tools 11, 13 are used as in the first embodiment of the invention. Thus, the part 3 is under the action of elastic stress in the region of the intermediate part 27, 27 ', 27 ", 27'" and is fixed relative to the shoulder 26, 26 ', 26 ", 26'".

In the first embodiment shown in FIG. 7, the intermediate part has a tapered recess 30, the inclined portion 29 of which directly communicates with the hole 28, i.e. without a flat plot.

Also in the second embodiment, the intermediate part 27 ', 27 ", 27'" may have a tapered recess 30 ', 30 ", 30'", an inclined section 29 ', 29 ", 29'" of which is not connected with the hole 28 ', 28 " , 28 '", and is separated from it by a ring 31', 31", 31 '". The ring may be located above the end of the inclined section 29 '(see ring 31') at the same height as the end of the inclined section 29 "(see ring 31") or above the end of the inclined section 29 '"(see ring 31'"). Of course, in this second embodiment, at the stage of deformation, the tool 13 is located opposite the inclined section 29 ', 29 ", 29'" and is not in contact with the ring 31 ', 31 ", 31'".

It is possible to combine the above embodiments of the invention depending on the application. In addition, this assembly can be used as a non-limiting example for an element of a clock mechanism, such as a ratchet mechanism, a travel regulator, a balancing spring, a jumper, or, more generally, for a set of gears.

It is also possible to use the described assembly instead of the elastic means 48 or cylinders 63, 66 described in document WO 2009/115463 (which is incorporated herein by reference) to fix a single spring-loaded balancing resonator on the hinge axis.

Of course, two elements similar to those described in this document can also be attached to the same axis using two separate catch to combine their respective movement.

And finally, the nodes of the invention can also provide fastening of any type of clockwork or other element, the case of which is formed of a material that does not have a ductility zone (silicon, quartz, etc.), with an axis, such as, for example, a resonator with a rotary fork, or, in a more general case, with a microelectromechanical system.

Claims (17)

1. A method of assembling an element (5, 15) made of a first material, with a part made of a second material that does not have a ductility region, comprising the steps of:
a) form part (3) with a hole (4);
b) insert an intermediate part (7, 27, 27 ', 27``, 27'''), which is made of a third material and has a hole (8, 28, 28 ', 28'',28''), in hole (4) without stress;
c) insert the element (5, 15) into the hole (8, 28, 28 ', 28``, 28''') without creating voltage;
d) deform the intermediate part (7, 27, 27 ', 27'',27''') elastically and plastic by moving two tools (11, 13, 21) towards each other in the axial direction, respectively, on the upper and lower parts of the intermediate part to create a radial stress (B, C) on the element and on the wall of the part (3) that causes elastic deformation of the part (3) to fasten the assembly without breaking the part. 2. The method according to claim 1, characterized in that the shape of the outer wall of the intermediate part (7, 27, 27 ', 27``, 27' '') essentially corresponds to the hole (4) in the part (3), which provides essentially radial stress (B) in the wall of the part (3) surrounding the hole (4). 3. The method according to claim 1, characterized in that the hole (4) of the part (3) is round. 4. The method according to claim 1, characterized in that the wall of the part (3) surrounding the hole (4) contains slots (1), which in step d) form micro-grooves on the outer surface of the intermediate part (7, 27, 27 ', 27``, 27 '' ') to prevent relative movement of the elements of the assembly. 5. The method according to claim 1, characterized in that the outer surface of the element (5) contains slots (1), which in step g) form micro-grooves on the inner surface of the intermediate part (7, 27, 27 ', 27' ', 27' '') to prevent relative movement of the elements of the assembly. 6. The method according to claim 1, characterized in that the hole (4) of the part (3) is asymmetric to prevent relative movement of the elements of the node. 7. The method according to claim 1, characterized in that in step b) the difference between the cross-section (e ₁ ) of the hole (4) and the outer cross-section (e ₃ ) of the intermediate part (7, 27, 27 ', 27'',27''') is approximately 10 μm. 8. The method according to claim 1, characterized in that in step c) the difference between the cross section (e ₂ ) of the element (5, 15) and the inner section (e ₄ ) of the intermediate part (7, 27, 27 ', 27'', 27 ''') is approximately 10 microns. 9. The method according to claim 1, characterized in that in step g), a compressive force arises due to deformation, causing a displacement of 16-40 microns. 10. The method according to claim 1, characterized in that in step b) the intermediate part (7, 27, 27 ', 27``, 27' ') has a tapered recess (10, 30, 30', 30 '', 30 '' '), coaxial with the hole (8, 28, 28', 28 '', 28 '' ') and designed to simplify in step g) the radial orientation (B, C) of the stress caused by the deformation of the intermediate part (7, 27, 27 ', 27``, 27' ''). 11. The method according to claim 1, characterized in that the second material is formed from a single-crystal silicon base 12. The method according to claim 1, characterized in that the third material is formed from a metal base or from a base of a metal alloy. 13. The method according to claim 1, characterized in that the part (3) is a set of gears of the clock mechanism. 14. The method according to claim 1, characterized in that the part (3) is a ratchet of a clockwork. 15. The method according to claim 1, characterized in that the part (3) is the balancing spring of the clock mechanism. 16. The method according to claim 1, characterized in that the part (3) is a resonator. 17. The method according to claim 1, characterized in that the part (3) is a microelectromechanical system.

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